1. Field of the Invention
This invention relates generally to data processing systems and, more particularly, to procedures within the data processing system for accumulating measurements of time for occurrences of a selected process.
2. Discussion of the Related Art
In a data processing system, it is frequently desirable to determine the length of time that the system is occupied in executing a selected process. It is known in the prior art to provide hardware apparatus coupled to the data processing system for the specific purpose of accomplishing such measurements. However, this apparatus is difficult to couple to the data processing system and can provide a potential source of damage to the data processing system. To avoid this problem, the measurements of the lengths of time that a processor spends implementing certain activities has been measured by internal software procedures in the data processing system. However, the software procedures have been unacceptably slow. Such a procedure loses much of its value when the measurement procedure requires an appreciable fraction of the activity time.
When internal data processing system processes are used to perform these measurements, a record is kept of the accumulated time for each occasion that the activity was present. This accumulated time is typically stored in a main memory location and is called the CUMUL field. The CUMUL field is the meter for the total time that the processor was involved in a selected activity. For each occasion that the activity is present in the processor, the CUMUL filed must be updated. The present invention relates to this updating procedure.
A need has therefore been felt for a cumulative measurement technique for an intermittent process that does not involve additional apparatus and which can be performed in a fraction of the time utilized by the activity being measured.